Magnetic separators



July 1, 1958 w. E. Box ETAL MAGNETIC sEPARAToRs Filed July 13, 1954 2 Sheets-Sheet l July 1, 1958 w. E. Box E'r-AL 2,841,285v

MAGNETIC SEPARATORS Filed July 13, 1954 2 Sheets-Sheet 2 /CWWWf/f www ,75.

2,841,235 Patented July l, 1958 MAGNETIC STIPARATORS Wiiiiam Edward Box, Erdington, Birmingham, and John Thomas Claridge, Sutton Coideld, England, assignors to Electromagnets Limited, Hoclrley, Birmingham, England, a company with limited liability incorporated under the laws of Great Britain Applicativi; `luly 13, 1954, Serial No.7443,072

Claims priority, application Great Britain June 29, 1954 Claims. (Cl. 209-223) This invention has reference to improvements relating to magnetic separators and is concerned particularly with magnetic separators of the kind in which the separated magnetic material is removed by means of a conveyor, usually in the form of an endless belt which passes around a source of magnetic energy located at the place where separation is to be effected.

Magnetic separators of the aforesaid kind as generally constructed heretofore incorporate a conveyor belt which is passed around either a magnetised pulley or a drum which is adapted to rotate about a stationary magnet.

Magnetic separators as aforesaid using a magnetic pulley are subject to the limitations that the magnetic ux has to emanate from the whole of the curved surface of the pulley and since the pulley is constantly rotating, a considerable portion of the magnetic energy is dissipated uselessly, and further since the cost of a magnetic pulley must necessarily depend upon the diameter of the pulley, the cost becomes disproportionate in the case where the circumstances necessitate the use of a large diameter pulley and consequently an increase in the wasted energy.

Magnetic separators as aforesaid which employ a drum adapted to rotate about a stationary magnet are not subject to the disadvantage ofthe magnetic pulley that the source of magnetic energy has to provide magnetic iluX around the whole curved surface but nevertheless the diameter of the drum determines the size of the source of magnetic energy so that the diameter of the drum again determines the cost and this cost once more may be disproportionately high in the case where circumstances require a drum of large diameter especially in the event of the use of the costly high intensity permanent magnetic materials now available.

With a View to overcoming the disadvantages of magnetic separators employing a magnetised pulley or drum as aforesaid, there has been described, illustrated and claimed in the speciication of our pending United States patent application Serial Number 191,620 led October 23, 1950, and now Patent No. 2,690,263, a magnetic separator of the kind referred to which provides the advantages of the magnetic pulley and of the drum type of magnetic separator without being subject to the limitations thereof, and which furthermore admits of the concentration at the place of separation of a eld of force, the intensity of which may be increased to any desired degree since the source (or sources) of magnetic energy is or are located between the runs of the conveyor and since the pole piece (or pole pieces) associated with said source (or sources) of magnetic energy are located between the runs of the conveyor adjacent to the place where separation is to be effected, the means for guiding the conveyor at the place of separation comprising a plurality of transversely arranged rollers of non-magnetic material which are rotatable within a plurality of transversely arranged indentations of arcuate formation provided in the pole piece (or pole pieces) with the rollers projecting slightly above the surface bounding the said indentations.

The present invention has for its object to provide in simpliied form a magnetic separator having the advantages of the magnetic separator described, illustrated and claimed in the specification of our pending United States patent application Serial Number 191,620 tiled October 23, 1950 and now Patent No. 2,690,263.

Accordingly the invention consists of a magnetic separator of the kind hereinbefore referred to in which at the place of separation the conveyor is guided by arotatable drum or pulley (or drums and/or pulleys) which are located between the poles of a source of magnetic energy which is located to the rear of the said drum or pulley (or drums and/or pulleys) and between the runs of the conveyor with the drum or pulley (or drums and/or pulleys) projecting beyond the arcuate outer ends of the pole piece (or pole pieces) for the said poles.

The invention also resides in a magnetic separator constructed, arranged and adapted for use substantially as will be described hereinafter.

The invention will now be described with particular reference to the accompanying drawings wherein:

Figure l is a diagrammatic View in side elevation of a magnetic separator in accordance with one embodiment of the invention utilising a permanent magnet means as the source of magnetic energy, p

Figure 2 is a plan of Figure l partly broken away for the sake of clearness,

Figure 3 is a diagrammatic View in side elevation of a magnetic separator in accordance with another embodiment of the invention utilising an electromagnet means as the source of magnetic energy,

Figure 4 is a plan of Figure 3 partly broken away for the sake of clearness,

Figure 5 is a similar View to Figure 3 showing a variation of the electromagnetic means incorporated in the embodiment illustrated in Figures 3 and 4,

Figure 6 is a plan of Figure 5 partly broken away for the sake of clearness, and

Figure 7 is a plan view showing the manner in which the magnetic means may be multiplied to any extent as may be required by the width of the conveyor belt.

In the drawings like numerals of reference indicate similar parts in the several views.

According to the embodiment of the invention illustrated in Figures l and 2 the source of magnetic energy comprises a stationary permanent magnet unit 10 of approximately U-shaped or yoke formation in plan which is located between the runs of an endless belt conveyor 11 adjacent to the discharge end, the said permanent magnet unit 10 comprising a transversely arranged rectangular block 101 of high intensity permanent magnetic alloy to the ends of which are connected in known manner the inner ends of forwardly projecting longitudinally arranged arms 102 of permanent magnetic alloy or of steel or of iron which constitute the pole pieces. These arms 92 are provided at their front ends with convex arcuate surfaces 103 of a radius of curvature slightly less than the radius of the path to be taken by the conveyor heit 11 at the place of discharge.

The arms i02 aforesaid are provided with transverse holes 104 which are located at the centres of curvature of the curved ends of the said arms 102 and these holes 104 serve to carry bearings for a transverse rotatable shaft 12 of non-magnetic material.

Fixed to the shaft 12 intermediate the arms 102 with the ends in close proximity thereto is a drum 13 of non-magnetic material of slightly greater radius than the radius of curvature of the arcuate ends 103 of the arms 102 aforesaid.

Fixed to the shaft 12 on the outer side of each of the arms 102 is 'a pulley 131 of non-magnetic material of the same radius as the drum 13' which is located intermediat Y the outer ends of the said arrs 192.

. kThe drum- 13 and'pulleys ,131 serve as the means for guiding the conveyor bel't'l at the place of discharge. The endless belt Y11 at the trailing end is passed around a drum 1d which is adapted to be driven by an electric Vmotor (not shown) in accordance with'the practice customarily adoptedin the case of magnetic separatorsof the endless belt conveyor type.

Thus the invention enables a magnetic field of the highest intensitytto be located atA the discharge end of the conveyor whilst the manner of mounting .the drum 13 around which the belt 11 is passed ensures that .theVV the fabricated permanent magnet runitY 1i) incorporated in the embodiment Irstdescribed and in this case the pole pieces are constituted by the longitudinallyl arranged arms 1% of angle section blocks of magnetic material,

Vthe transversellimbs 167 of whichY serve asabutments .for

the cores of a `pair of parallel longitudinally arranged energising coils 108, the other ends of the said cores 108 `being Ysecured to a transverse rectangular block 169V of Y, magnetic material Yarranged to the coils 168.. Y

'Y The outer ends of therarms 106 are arcuate' as indi-'- cated at 103 and the said arms 166 support a rotatable` shaft 12 of non-magnetic'material on which is xed a drum 13 and pulleys 131 in a manner analogous to' that in theA embodiment first described..

In Ythe case of the further embodiment ofthe invention VVillustrated in Figures 5 and anelectromagnet unit 15 is employed again as the source of magnetic ux but ,theY

energising coil 108 is arranged transverselyof theV conveyor belt 11 and with'theinner ends of the arms 106 in abutment with the respective ends of the `core oanV energising coil 108 soarranged. Y Y

If the width of the conveyor belt 11 so requires; a

plurality of magnetic means arrangedV side by, side to extend the full width of the said belt 11 may be employed, Y as is illustrated in Figure 7 where the source of magnetic flux is a battery of transversely arranged fabricatedfper 7 marient magnets 10, each of which is similar to the rear of the saidY permanent magnet unit 10 described with reference toV `Y Figures Vl and 2 which are arranged side by'side with drums 13 and pulleys 131 arranged between the arms Magnetic separators in accordance with the invention` possessthe advantages of the intense magnetic eld pro-k duced by the arrangement of the magnetic source between the runs of a conveyor as disclosed in the specification of our pending United States patent rapplication Serial VNumber 191,620 -led October 23, 1950 andN now PatentV No. 2,690,263, but dispenses with the need `for a polev piece having-transversely arranged indentations in which are housedl rotatable rollers for guiding the belt around the poles in the said prior invention. v

Instead of a built-up permanent magnet or magnets as illustrated in Figures 1, 2 `and 7, the permanent magnet unitmay be constituted as a single piece horse-shoe'magi net or magnets Vof permanent magnetic material, but owing to the expense of the high intensity permanent magnetic alloys theV fabricated permanent Amagnet unit is torbe preferred.

We claim: j j V LA magnetic separator comprising an endless conveyor band extending longitudinally/'ina horizontal plane supported at the discharge end by a plurality of at .least three pulleys spaced transversely on an axle, Asaid ccnvcyor band, said pulleys, and said axle being made of materials having substantially the same magnetic permeability as air, and a stationary magnet with arms projecting into the spaces between. saidpulleysand terminating in pole' pieces having convex curvature,V concentric with the circumference osaid pulleys With radius slightly smaller than the radius of said pulleys and located adja-V cent said conveyorY band where said Vvconveyor band is supported by said pulleys, said stationary Vmagnet being yoke-shaped in contour and having its arms connected by a transverse magnetic section located to therear rof said pulleys.Y Y 1 2. A magnetic separator according to claim l wherein; said axle is supported by bearing means located in Vsaid pole pieces. y p

3.' A magnetic separator according to claim l wherein said stationary magnet is a permanent magnet.

4. A 'magnetic separator according to Vclaim l' wherein the polarity of adjacent poles `is opposite'. Y 5. A magnetic separator according to claim l wherein said pole pieces have transverse Aholes at. the center of` their convex curvature, said holes serving to carry bearings for said axle.

6. A'vmagnetic separator comprising anpendlessconl` Veyor band extending longitudinally in ahorizontal plane supported at the discharge end byl a plurality of'at least three pulleys spaced transversely on an axle, said'con;

veyor band, said pulleys, and said .axle fbeing'madeof., materials having substantiallythe sameV magnetic permeability as air, and a plurality ofrtransvers'ely arranged" stationary magnets witharms projecting into theY spaces between said pulleys audterminating in pole' piecesghav-V ing convex curvature concentric with thercircumfer'ence' of said pulleys with a radius slightly smaller thantheA radius of said pulleys and located adjacent said conveyor.` band where said conveyorband is supported bysa'id pulleys, each of said stationary magnets being'yolte-shaped' in contour Yand each having its arms 'connectedf'by a'V transverse magnetic section located Yto thefrearoijsaidV pulleys. g c 7. A magnetic separator according to claim-6 wherein saidpole pieces have transversep'holesV at the `center of`V their curvature, said holes serving to carryf'bea'r'ingsior said axle. Y 8. A magnetic separator according to--claim -6 wherein said axle is supported by bearing means located in saidYY pole'pieces.

9. A magnetic separator according to claim 6 wherein said stationary magnets are permanent magnets.y n

' 10. A lmagnetic separator according to claim 6 wherei each magnet has onlyrtwo pole pieces, said pole piecesof each magnet having opposite polarity.` f

References Cited -in the file of this patentY UNITEDLsrATEs PATENTS 481,474 senkung Aug. 23; 1:1972:v 971,163 weedV sept. 27, 1910 1,531,372 Beurk@- Mar. 31, 192s Y l Y FORErGN PATENTS 1,079,403 1,954 

